In the game of process control, one pays attention to all the variables or at least all of the ones you can identify.

Every variable you have identified has an impact on the final result. It is very hard to identify the magnitude of each of the variables you have identified.

What is implied, but not said, is the consistancy with which you incorporate your attempts to control these variables.

What is required is accurate data to support your theories.

I try to use brass, bullets, primers and powder from the same lots to achieve consistancy.

I keep records of components and how the results stack up.

I get into a routine.

New brass gets sized and trimmed.
Necks get chamfered.
Bullets come from a single manufacturer.
Powder comes from a single manufacturer.
Bullets are seated at the same depth.
Loads are weighed every fifth cartridge.
Box labels are accurate.
Records are kept of results.

Those results tell me if I should be working to identify other variables.

Shot brass stays with the same rifle.
Brass is spot checked for length after every firing. If any approach max length, they are all trimmed.

The quest for accuracy is never ending. All you can do is try to minimize the effect of every identifiable variable.

The only way you can tell if your efforts are doing any good is to keep very good records.

It is fun and it is time consuming, but also very satisfying to see the groups get smaller.

Geetar you're talking about variables that effect the minute changes in accuracy. He's asking about the biggest factor if I read it right. I try to do the same things you do to an extent but the one thing that I know is that if I don't have the same amount of bang-bang dust in each cartridge, the results will be different.

Trying to identify one thing that makes a load accurate is like trying to determine which single item is necessary for sustained life. Man cannot live very long without food, water, air, etc. Which blade of grass in your lawn makes it look the best?

As has already been indicated, there are many things that contribute to great accuracy of any load. Each component plays it's part in it and if you throw any one of them out your accuracy would suffer greatly.

The single thing I would identify for accuracy building would be "paying close attention to what you are doing". Carelessness can really ruin your day.

You have to start with a good bullet. Both Hornady and Sierra have given me very good results without spending too much money.

Then I have to find the optimum charge weight for whatever powder I decide to use. And then stick close to that optimum powder weight. But some combos of powder/bullet have a very narrow "sweet spot" while some of them have a much wider sweet spot. I like the wide sweet spot much better of course. If that sweet spot is only 0.2 gr wide, then you have to be very meticulous about duplicating it. The other day I was testing some loads and found a very wide sweet spot using H4831 in my 270 WSM. I can go up or down by 0.6 gr from the optimum weight without significant changes in the group. That is very nice later on to know that you don't have to trickle it in down to the last 0.1 gr.

I personally haven't noticed any difference with primers, but I haven't experimented with them a whole lot, using mostly CCI and Winchester.

I have played around with the seating depth relative to the lands. It does change the accuracy a little bit, but if you have found a good optimum charge weight with a broad sweet spot, the seating depth is not as important.

Me personally, I like consistent brass, I trim it each time. I no longer waste time neck turning with factory chambers, but do standardize primers pockets once. Some of the last batch of Nosler brass for my 223's is every bit as good as the Lapua.

I lack in record keeping as evidenced from some of these posts. I keep the targets with the recipes written on them but not lot numbers and such.

Thanks for the new info.

__________________
"Happiness is knowing the Barred Owl is Eating the Spotted Owl and environmentalists are watching Nature take it's course"

Obviously we can all agree that it's everything that matters the most. Kind of like the weakest link in a chain, ya know? But the original post did specify that we try to pinpoint one thing that has the most effect on accuracy.

In my opinion, I would have to say that it's the quality of the bullet and how consistently you seat that bullet. I think that is where the most accuracy is to be gained or lost.

Everything is a factor and I would be willing to bet for a lot of shooters that technique when testing those loads is a huge factor, but if we have to narrow our pick down to one component or process, I would say it's about the projectile... the quality of it, the seating depth, the case mouth tension and the concentricity of it when seated.

But honestly? That's just what I think. I don't have any proof.

__________________Attention Brass rats and other reloaders: I really need .327 Federal Magnum brass, no lot size too small. Tell me what caliber you need and I'll see what I have to swap. PM me and we'll discuss.

I think the most important part of accuracy loading is the handloader himself. If the person reloading knows what he or she is doing then the accuracy will come. A knowledgeable handloader will know how to make the best and most accurate handloads.

Time, time is a factor, in my rifles time is the BIG FACTOR, in my rifles the firing pin crushes the primer before the case, bullet and powder knows their little buddy has been crushed, such as it is when time is a factor.

It wares me out keeping the barrel on task, so I have magic firing pins, those without magic firing pins are exempt and time is not a factor.

I have two rifles chambered in 300 Win Mag, one is a non-Weatherby the other is a Model 70 Winchester, the difference in the two? The Weatherby shoots one hole groups, the Model 70 shoots patterns (as in shotgun type patterns) with the same ammo, the difference? Time.

No 'single thing' makes any ammunition, reloaded or otherwise, accurate or inaccurate- but an undersized bullet will never shoot particularly well.

__________________
“Nine-tenths of tactics are certain, and taught in books: but the irrational tenth is like the kingfisher flashing across the pool, and that is the test of generals. It can only be ensured by instinct, sharpened by thought practicing the stroke so often that at the crisis it is as natural as a reflex.” ~ T. E. Lawrence

Everything is a factor and I would be willing to bet for a lot of shooters that technique when testing those loads is a huge factor

The most precise handloads don't mean squat if the shooter is testing off the hood of his car/truck. Or he had way to much to drink the night before.

Now assuming he has a good solid bench, at the bare minimum some sand bags front and rear, and low wind conditions, he can test those handloads.

There's so many variables that factor into what the final group looks like that listing them all is futile. Much easier to list the things NOT TO DO! That's a long list as well.

Criteria is another thing. Are you looking to make small groups at 600 yds? Or are you simply loading for a hunt where you seldom see a 100 yd. shot? Minute of deer hide is a much larger number that minute of angle @ 600 yds.

When loading for a new rifle, I spend a lot of time looking in loading manuals AFTER deciding what I want that rifle OR handgun to do. Selecting bullet type, I then look for the best powder for that application. Brass, bullets, and dies are ordered, by the time they arrive, I have the load picked out.

Since I've been loading for almost 50 years, I already have a large selection of powder and primers on hand. I sometimes bite on some new super-powder, which I buy locally.

The rest is trying different loads and testing. But that's the fun part, um, that's why we do it, isn't it?

__________________
The more people I meet, the more I love my dog

They're going to get their butts kicked over there this election. How come people can't spell and use words correctly?

This email link is to reach site administrators for assistance, if you cannot access TFL via other means. If you are a TFL member and can access TFL, please do not use this link; instead, use the forums (like Questions, Suggestions, and Tech Support) or PM an appropriate mod or admin.

If you are experiencing difficulties posting in the Buy/Sell/Trade subforums of TFL, please read the "sticky" announcement threads at the top of the applicable subforum. If you still feel you are qualified to post in those subforums, please contact "Shane Tuttle" (the mod for that portion of TFL) via Private Message for assistance.

This email contact address is not an "Ask the Firearms Expert" service. Such emails will be ignored. If you have a firearm related question, please register and post it on the forums.